Soldering station with automatic soldering connection validation

ABSTRACT

A soldering iron station and a method thereof for a soldering joint connection validation, the method including: identifying a type of the soldering cartridge being used; performing a preliminary validation by measuring the soldering tip temperature, after the soldering event has started; monitoring the power level delivered to the soldering tip to detect liquidus occurrence; determining the thickness of an intermetallic component (IMC) of the soldering joint; determining whether the thickness of the IMC is within a predetermined range, within a predetermined cooling time period; and indicating that a reliable soldering joint connection is formed, when the thickness of the IMC is within the predetermined range, within the predetermined cooling time period.

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application is a continuation of U.S. patent applicationSer. No. 14/794,678, filed on Jul. 8, 2015, which claims the benefit ofthe filing date of U.S. Provisional Patent Application No. 62/033,037,filed on Aug. 4, 2014, the entire contents of all of which are herebyexpressly incorporated by reference.

FIELD OF THE INVENTION

The present invention relates generally to manufacturing, repair andrework of printed circuit boards (PCBs); and more particularly to asoldering iron with automatic soldering connection validation.

BACKGROUND

With the greater variety of components used on printed circuit boards(PCBs), smaller passive components and larger ICs with finer ball pitchdimensions, the demands on high quality solder joints to aid PCBassembly (PCBA) fabrication and rework have increased. Faulty solderjoint has cost companies billions of dollars over the years. Manyprocesses have been developed to reduce failure rate for wave soldersystems. However, for point to point handheld soldering and reworkapplications, companies are purely relying on operators' skills toproduce good solder joints with quality electrical connections.Regardless of how much training is provided to the operators of thesoldering iron, without guidance during a soldering activity, theoperators may make and repeat mistakes due to the fact that there aremany factors that impact heat transfer by the soldering iron for forminga solder joint with good electrical connection. These factors includesolder tip temperature, geometry of the solder tip, oxidation of thesolder, human behavior, and the like.

SUMMARY

In some embodiments, the present invention is a method performed by ahandheld soldering iron station for a soldering joint connectionvalidation, the handheld soldering iron station including a solderingcartridge having a soldering tip. The method includes: identifying atype of the soldering cartridge being used by the soldering iron stationand obtaining information related to the identified cartridge;determining that a soldering event has started by measuring a powerlevel delivered to the soldering tip, within a first predetermined timeperiod; performing a preliminary validation by measuring a soldering tiptemperature, after the soldering event has started; monitoring the powerlevel delivered to the soldering tip to detect liquidus occurrence;determining a thickness of an intermetallic component (IMC) of thesoldering joint as a function of soldering time and soldering tiptemperature, after detect the liquidus occurrence; determining whetherthe thickness of the IMC is within a predetermined range, within apredetermined cooling time period; and indicating that a reliablesoldering joint connection is formed, when the thickness of the IMC iswithin the predetermined range, within the predetermined cooling timeperiod.

In some embodiments, the present invention is a soldering iron stationwith automatic soldering joint connection validation including: a handpiece including a soldering cartridge having a soldering tip; a powersupply for delivering power to the soldering tip; an indicator; and aprocessor including associated circuits for identifying a type of thesoldering cartridge being used by the soldering iron station andobtaining information related to the identified cartridge; performing apreliminary validation by measuring a soldering tip temperature;monitoring the power level delivered to the soldering tip to detectliquidus occurrence; determining a thickness of an intermetalliccomponent (IMC) of the soldering joint as a function of soldering timeand soldering tip temperature, after detecting the liquidus occurrence;and determining whether the thickness of the IMC is within apredetermined range, within a predetermined cooling time period. Theindicator indicates that a reliable soldering joint connection isformed, when the thickness of the IMC is within the predetermined range,within the predetermined cooling time period.

In some embodiments, the present invention is a method performed by ahandheld soldering iron station for a soldering joint connectionvalidation, the handheld soldering iron station including two camerasfor capturing respective images of the soldering joint from differentviews. The method includes: capturing a 2-dimensional (2D) referenceimage of the soldering joint by each of the cameras, before a solderingevent starts; generating a 3-dimensional (3D) reference image of thesoldering joint from the captured 2D reference images; determining anamount of solder needed to fill in a barrel of a hole for a through holecomponent, or to fill in a surface of a barrel of a hole for a surfacemount component, from the 3D reference image; capturing a 2D currentimage of the soldering joint by each of the cameras, after the solderingevent starts; comparing a value of each pixel in each of the 2D currentimages to corresponding pixel values in the 2D reference images,respectively to detect any color changes of the pixels in the 2D currentimages due to spread of a dispensed solder, as the soldering eventprogresses; repeating capturing a 2D current image and comparing a valueof each pixel, until all the pixels in the 2D current images aredetermined to be pixels of the dispensed solder to detect an occurrenceof a liquidus of the dispensed solder; after detection of the occurrenceof the liquidus, generating a 3D current image of the soldering jointfrom the last captured 2D reference image from each camera; determiningvolume of the dispensed solder after occurrence of the liquidus from the3D current image; comparing the volume of the dispensed solder to thedetermined amount of solder needed to fill in the barrel or the surfacearea of the barrel to determine how much of the dispensed solder isdissipated into the barrel or on the surface area of the barrel;repeating the comparing of the volume of the dispensed solder until thedispensed solder has filed the barrel or the surface area of the barrel,within a predetermined tolerance; and activating an indicator toindicate a good connection, when the dispensed solder has filed thebarrel or the surface area of the barrel within the predeterminedtolerance.

In some embodiments, the present invention is a soldering iron stationwith automatic validation of connection of a soldering joint comprising:a hand piece including a soldering tip; a power supply for deliveringpower to the soldering tip; two cameras positioned at differentlocations, each for capturing a 2-dimensional (2D) image of thesoldering joint; an indicator; and a processor including associatedcircuits for validation of the connection of the soldering joint. Eachof the cameras captures a 2-dimensional (2D) reference image of thesoldering joint by each of the cameras, before a soldering event starts;the processor generates a 3-dimensional (3D) reference image of thesoldering joint from the captured 2D reference images and determines anamount of solder needed to fill in a barrel of a hole for a through holecomponent, or to fill in a surface of a barrel of a hole for a surfacemount component, from the 3D reference image; each of the camerascaptures a 2D current image of the soldering joint, after the solderingevent starts, the processor compares a value of each pixel in each ofthe 2D current images to corresponding pixel values in the 2D referenceimages, respectively to detect any color changes of the pixels in the 2Dcurrent images due to spread of a dispensed solder, as the solderingevent progresses, each of the cameras repeats capturing a 2D currentimage and the processor repeats comparing a value of each pixel, untilall the pixels in the 2D current images are determined to be pixels ofthe dispensed solder to detect an occurrence of a liquidus of thedispensed solder, after detection of the occurrence of the liquidus, theprocessor generates a 3D current image of the soldering joint from thelast captured 2D reference image from each camera, determines volume ofthe dispensed solder after occurrence of the liquidus from the 3Dcurrent image, compares the volume of the dispensed solder to thedetermined amount of solder needed to fill in the barrel or the surfacearea of the barrel to determine how much of the dispensed solder isdissipated into the barrel or on the surface area of the barrel, andrepeats the comparing of the volume of the dispensed solder until thedispensed solder has filed the barrel or the surface area of the barrelwithin a predetermined tolerance. The soldering station further includesan indicator to indicate a good connection, when the dispensed solderhas filed the barrel or the surface area of the barrel within thepredetermined tolerance.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A depicts an exemplary handheld soldering iron, according to someembodiments of the present invention.

FIG. 1B is an exemplary block diagram of a processor and associatedcomponents, according to some embodiments of the present invention.

FIG. 2 shows an exemplary process flow, according to some embodiments ofthe present invention.

FIG. 3A shows a graph for a change in temperature of a soldering tipover time, for three given load sizes, according to some embodiments ofthe present invention.

FIG. 3B depicts a graph for a change in impedance of a soldering tipover time, for three given power levels and three given temperatures,according to some embodiments of the present invention.

FIG. 4A illustrates a graph for the thickness of the IMC versus time,according to some embodiments of the present invention.

FIG. 4B illustrates a graph for the thickness for the IMC versussoldering time, according to some embodiments of the present invention.

FIG. 5 is an exemplary process flow for liquidus detection andconnection verification using images from a plurality of cameras,according to some embodiments of the present invention.

FIGS. 6A-6D show various images used for detection of liquidus,according to some embodiments of the present invention.

FIG. 7A shows some exemplary solder joints for through hole components,according to some embodiments of the present invention.

FIG. 7B depicts some exemplary solder joints for surface mountcomponents, according to some embodiments of the present invention.

DETAILED DESCRIPTION

In some embodiments, the present invention is a soldering iron withautomatic soldering connection validation. The soldering iron includes aprocessor, such as a microprocessor or controller, memory, input/outputcircuitry and other necessary electronic circuitry to perform thesoldering connection validation.

In some embodiments, the processor receive various characteristics ofthe soldering joint and soldering iron and performs a process ofcalculating the intermetallic IMC thickness of solder and PCB substrateto ensure a good solder joint is formed during a soldering event. Once agood electrical connection for the solder joint is confirmed, an audioor LED indicator in the soldering iron, for example, in a hand piece,informs the operator of the formation of the good solder joint.Typically, a good solder joint formed by SAC solder and copper substratePCB is when the intermetallic thickness is within 1 um-4 um.Accordingly, if the operator uses, for example, SAC305 (96.5% Sn, 3% Ag,0.5% Cu) solder wire with copper substrate PCB, intermetallic thicknessCu₆Sn₅ is calculated by some embodiments of the present invention andthe operator is notified once the intermetallic thickness of theintermetallic compound (IMC) reaches 1 um-4 um, during the soldering.

The chemical reaction between the copper substrate and the solderingiron can be shown as:

3Cu+Sn->Cu₃Sn(phase 1)  (1)

2Cu₃Sn+3Sn->Cu₆Sn.(phase 2—IMC 1 um-4 um)  (2).

Phase 1 of the chemical reaction is temporary (transient) and thereforeis not used for determination of the quality of the solder joint.

In some embodiments, the microprocessor (or the controller) may beplaced in the power supply, in the hand piece, or a stand of thesoldering system. Communication with external devices, such as a localcomputer, a remote server, a printer and the like, may be performed atthe work stand by wired and/or wireless connections, using the knownwireless interfaces.

FIG. 1A depicts an exemplary handheld soldering iron, according to someembodiments of the present invention. As shown, the handheld solderingiron includes a power supply unit 102 including a display 104, forexample an LCD display, and various indicators 106, such as LEDindicators 106 a and 106 b. The soldering iron further includes a handpiece 108 coupled to the power supply unit 102 and a (work) stand 11that accommodates the hand piece 108. The hand piece 108 receives powerfrom the power supply unit 102 and heats up a soldering tip to performthe soldering on a work piece. In some embodiments, the soldering tipmay include a temperature sensor to sense the tip temperature andtransmit that data to the processor.

The hand piece 108 may include various indicators such as one or moreLEDs and/or a buzzer on it. In some embodiment, the power supply unit102 includes a microprocessor, memory, input/output circuitry and othernecessary electronic circuitry to perform various processes.

In some embodiments, the microprocessor and the associated circuitsidentify what soldering cartridge is being used, validate the tipgeometry, validate that the temperature and load are matched to ensurethat the cartridge can produce sufficient energy to bring the load tosolder melting point, detect liquidus temperature and then determine thethickness of the IMC, as described in more detail below. In someembodiments, the soldering cartridge includes the soldering tip,associated wiring, magnetic shield, heater, shaft, connector(s), anon-volatile memory (NVM), one or more sensors, and a potentiometer tomeasure the impedance of the tip. The liquidus temperature is thetemperature above which a material is completely liquid. Liquidustemperature is mostly used for impure substances (mixtures) such asglasses, alloys and rocks. Above the liquidus temperature the materialis homogeneous and liquid at equilibrium. Below the liquidustemperature, more crystals are formed in the material after a sufficienttime, depending on the material.

FIG. 1B is an exemplary block diagram of a processor and associatedcomponents, according to some embodiments of the present invention. Asillustrated, a processor 112, a memory 114 a non-volatile memory (NVM)116 and an I/O interface 118 are coupled to a bus 120 to comprise theprocessor and associated circuitry of some embodiments of the presentinvention. The I/O interface 118 may be a wired interface and/or awireless interface to components external to the soldering station.Optionally, two cameras 122 and 124 are coupled to the processor and thememory via the bus 120 or the I/O interface 118 to capture images from asolder joint from different views. Additionally, an optional temperaturesensor 126 for sensing the temperature of the soldering tip may becoupled to the processor 112 and the memory 114 via the bus 120 or theI/O interface 118.

FIG. 2 shows an exemplary process flow, according to some embodiments ofthe present invention. As shown in block 202, The process for validatingall the connections joint between the component and the PCB substratestarts. In block 204, the cartridge being used is identified and thedata related to the identified cartridge is retrieved from anon-volatile memory (NVM), such as an EEPROM. In some embodiments, theNVM may be placed in the cartridge to store data related to thecartridge such as, part number, lot code, serial number, total usage,total point, tip mass/weight, tip configuration, authentication code (ifany), thermal efficiency, thermal characteristic, and the like. Thisdata may be retrieved periodically at the startup and during theoperation. In some embodiments, the data may also be received andtransmitted via wire or wireless methods.

In block 206, checks the power level to determine whether any solderingaction is being performed, within a period of time. If no solderingaction to be performed yet, the process waits in block 206. For example,a timer can be set to a predetermined time and if no action happenswithin that time, the process waits. However, if a soldering action tobe performed, the process proceeds to an optional block 208, where theindicators are reset.

FIG. 3A shows a graph for a change in temperature of a soldering tipover time, for three given load sizes. Graph 306 is for a large loadsize, graph 304 is for a medium load size and graph 302 shows a smallload size. As illustrated in FIG. 3A, for a given tip, the heavier theload, the higher temperature drop. In some embodiments, if the tiptemperature drop is greater than a predetermined value, for example, 25°C., the process is aborted since the power supply would be unable torecover fast enough to continue delivering power to the tip to maintainthe temperature of the tip, within the required time to complete thesoldering event (e.g., 8 seconds).

In some embodiments, the temperature drop may be detected by measuringthe impedance of the tip and then determining the tip temperature by theequation (3) below. The impedance may be measured by turning off thepower to the tip and measuring the voltage of the coil (in thecartridge). The impedance would then be the voltage of the coil times amImpedance Factor (K in Equation (3)), which would depend of the tiptype. In some embodiments, a temperature sensor may be placed in the tipto directly read the temperature drop and communicate it to themicroprocessor.

R _(imd) =R _(min) +R _(max)/{1+[k*ê(−T)]}  (3).

Where, R_(imd) is the impedance value, R_(min) is a minimum value of theimpedance, R_(min) is a maximum value of the impedance, K is a weightfactor and T is delta temperature.

FIG. 3B depicts a graph for a change in impedance of a soldering tipover time, for three given power levels that are delivered by the powersupply unit to the soldering tip and three given temperatures of thesoldering tip. Graph 318 is for a small power, graph 312 is for a largepower and graph 314 shows a medium power. Moreover, graph 310 is for asmall temperature, graph 316 is for medium temperature and graph 320 isfor a large temperature.

In some embodiments, the temperature drop may be detected by defining athermal efficiency factor for each given tip geometry and heatermaterial, as shown in Equation (4) below. If power draws higher thanTE_factor, the system determines an abort in the process by, forexample, turning on a red LED and/or a buzzer.

TE_factor=TipMass*TipStyle*HTR_factor*Const  (4),

where, TipMass is the copper weight (mg), which is 0.65 for a“LongReach” tip, 1 for a “Regular” tip, and 1.72 for a “Power” tip.TipStyle refers to the distance from the tip of tip to the heater in thecartridge. For example, TipStyle is 20 mm for a “LongReach” tip, 10 mmfor a “Regular” tip, and 5 mm for a “Power” tip. HTR_factor is theheater temperature times a factor (e.g., 0.01), which changes based onthe type of the heater. Const=4.651*10⁻³ for all types of heaters. Forexample, the HTR_factor may be 800 F*0.01=8; 700 F*0.01=7; 600 F*0.01=6;or 500 F*0.01=5 for various heater types.

Referring back to FIG. 2, in block 210, a thermal efficiency check isperformed to ensure that the tip geometry/temperature and the load arematched, based upon tip temperature drop within a predetermined timeperiod, for example, the first 2-3 seconds. In some embodiments, thethermal efficiency check checks the heat transfer and power recovery ofthe soldering station with respect to the tip and the load. Each tiptype has its own thermal characteristic, which is a function of the tiptemperature, mass, and configuration/style. For various tip types, theirthermal efficiency factors (TEs) are stored in the NVM. During the firstperiod of time (e.g., 2-3 seconds), the power to the tip is measured andcompared with the TE of the tip. If the measured power is greater than athreshold value, for example, 95%+/−10% of TE, it means that the tip istoo small or the load is too large, become they require a lot of power.In this case, the thermal efficiency check fails (210 a), the process isaborted in block 226 and optionally one or more indicators, for example,a red LED and/or a buzzer, are turned on. If the thermal efficiencycheck passed (210 b), the process proceeds to the optional block 212where a “passing” indicator, such as a green LED and/or a beep, isturned on to let the operator know that the thermal efficiency checkprocess has passed.

In block 214, the liquidus temperature is detected based on thefollowing heat transfer equation.

ΔT=P*TR  (5),

where, ΔT is the tip temperature minus the load temperature, P is thepower level, and TR is the thermal resistant between the tip and theload that may be retrieved from the NVM.

Since load temperature continues to increase until it reachesequilibrium, ΔT decreases throughout the soldering action. Also, powerincreases when the soldering event first starts. Therefore, TR will bedecreasing, as shown below. Once liquidus occurs, TR is stabilized andthus the power P now starts decreasing, as shown below. Accordingly, todetect liquidus temperature, the change state in the power delivered tothe soldering tip is observed.

ΔT↓=P↑*TR↓

ΔT↓=P↓*TR˜

In block 216, it is checked to see if the power is at a peak anddeclining. If not, the process is timed out (216 a) and aborted in block226. If the power is at a peak and declining, the process proceed toblock 218 to turn on an indicator, for example, an LED and/or a beepsound. When the power is at a peak and declining, it means that thesolder event is at liquidus state.

In block 220, the thickness of the IMC is determined by the followingequation.

IMC=1+[k*ln(t+1)]  (6),

where k is a weighing factor and t is solder interval time @100 ms.

Generally, the thickness of the IMC would be a function of time andtemperature.

When the temperature is at melting point (e.g., at 220-240° C.), it doesnot have a substantial impact on the thickness of the IMC. Accordingly,Equation (6) is based on only time and a fixed temperature.

FIG. 4A illustrates a graph for the thickness of the IMC versus time,for k=0.2173, which is obtain by experimentation, using many solderingjoint and IMC thickness measurement. As depicted in FIG. 4A, the IMCthickness increases over time.

Referring back to FIG. 2, block 222 checks to see whether within apredetermine amount of time (cooling period), the determined thicknessof the IMC is within a predetermined range, for example, 1 um to 4 um.If it is, the processes proceeds to block 224, where the operator isinformed. If the result of the test in block 222 is false, the processis timed out (222 b) and aborted in block 226.

In some embodiments, the invention provides the operator with anindication of successful or potential non-successful joint formation,along with the ability to collect the intermetallic joint information,and the operational parameters for that particular joint for postprocessing. Indication can be accomplished via visual means, audiblemeans, and/or vibration of the hand piece.

A debug mode (block 228) is used, for example, by a process engineer tokeep track of the steps involved during a solder event. To enter thedebug mode, a user needs to turn the debug mode on.

FIG. 4B illustrates a graph for the thickness for the IMC versussoldering time. As depicted, graph 402 is for a temperature of 300° C.with Y=0.176X+1.242, graph 404 is for a temperature of 275° C. withY=0.044X+1.019, and graph 404 is for a temperature of 220° C. withY=0.049X+0.297, where X is the time and Y is the IMC thickness. Theconstant numbers are derived from multiple experimentations. As shown, abreak out of the IMC thickness happens at three different temperatureranges. Since the thickness of the IMC is a function of time andtemperature, as temperature rises, the IMC grows larger, as a linearfunction. Depending on the application, any of these curves may be usedto determine the weighing factor, K, in Equation (6). For example, for asoldering application with SAC305 tip, graph 404 is used.

This way, the embodiments of the present invention ensure a good bondingand electrical connection between two metals by calculating theintermetallic thickness and therefore prevent a bad joint in earlystages. Moreover, the invention provides instant feedback (by theindicators) to operators on joint quality and process issues and thusthe operators have the ability to track information on joint quality forpost analysis. The operators can change or select from a menu severalparameters to meet certain application requirements.

In some embodiments, when a Curie temperature (point)/Smartheat™technology, which is a self-regulated Curie temperature, is utilized,there is no requirement for calibration of the system at customer site.The Curie temperature or Curie point, is the temperature where amaterial's permanent magnetism changes to induced magnetism, that is,the critical point where a material's intrinsic magnetic moments changedirection. The invention also provides the capability to help theoperators to identify whether they are using an improper tip/cartridgecombination for a soldering event

In some embodiments, the invention uses at least two high resolutioncameras to capture two or more 2D images, obtain a 3D image from those2D images, use the 2D and 3D images to detect liquidus stage and thencalculate the amount of solder filled through the via hole (barrel) forthrough hole components, or the amount solder spread out around thecomponents for surface mount components.

FIG. 5 is an exemplary process flow for liquidus detection andconnection verification using images from a plurality of cameras,according to some embodiments of the present invention. At least twohigh resolution cameras are placed close to the soldering joint at twodifferent locations to capture 2D images of the solder joint from twoviews, before and after the soldering event. The liquidus is detectedfrom comparison of the 2D images. Then, in the case of through holecomponents, the volume of the through hole barrel (barrel) is determinedfrom 3D images generated from the 2D images. In the case of surfacemounted (SMT) components, the surface of the barrel on the PCB isdetermined from the 2D images. As shown in block 502, two images of thesoldering area (joint) are captured by the two cameras, before thesoldering event to generate two reference images, as depicted in FIG.6A. In block 504, a 3D reference image of the soldering area isgenerated from the two reference images, before the soldering event, bywell know methods.

In block 506, the volume of the barrel V_(b) for through hole and/or thesurface area of the barrel S_(b) for SMT component are determined fromthe 3D reference image to determine how much solder is need to fill thebarrel or the surface area of the barrel. The surface of the barrel mayalso be determined from the 2D images, depending on the camerapositions. Accordingly, the amount of solder needed to fill in thebarrel or the surface of the barrel is determined, depending on the typeof the component. Immediately after the soldering event is started, twocurrent images of the soldering area is captured, in block 508. In block510, the color value of each pixel in the 2D reference images iscompared to color value of each corresponding pixel in the 2D currentimages, as the soldering event progresses, to detect any color changesof the pixels in the current images due to spread of the solder. Sincethe pixel value of the solder color is known, this the process candetermine whether a pixel is a solder pixel, i.e., contains solder, asshown in FIG. 6B.

In block 512, the processes in blocks 508 (FIG. 6C) and 510 are repeateduntil all the pixels in the current images are determined to be pixelsof the dispensed solder, that is, the liquidus is now detected, asdepicted in FIG. 6D. The process in block 512 is timed out after apredetermined amount of time (e.g., 8 seconds), if not all the pixels inthe current images are determined to be pixels of solder. When all thepixels in the last two current images are determined to be pixels of thedispensed solder (within a tolerance range), the liquidus is detected,in block 514.

After the detection of the liquidus, the last current image from eachcamera are processed to generate a 3D current image, in block 516. Then,the volume of the dispensed solder V_(s) is determined from the 3Dcurrent image, by one or more of Equations (7) to (9), in block 518. Inblock 520, the calculated volume of the dispensed solder V_(s) iscompared to the determined amount of solder needed to fill in the barrel(i.e., V_(b)) or the surface area of the barrel (i.e., S_(b)) todetermine how much of the dispensed solder is dissipated into the barrelor on the surface area of the barrel. This process (block 520) isrepeated in block 522, until the dispensed solder has filed the barrelor the surface area of the barrel. That is, the volume of the visibledispensed solder has reached (V_(s) Vb) or (V_(s) S_(b)), within apredetermined tolerance range. The process in block 522 is timed outafter a predetermined amount of time (e.g., 8 seconds). An indicator(e.g., a LED and/or beep) is then turn on to notify the operator thatthe connection is now formed by filling all of the barrel or the surfaceof the barrel with the dispensed solder.

In other words, in the case of a through hole component, when thecalculated volume reduces to a predetermined amount that is needed tofill the barrel and within a pre-defined tolerance for through holecomponent, a good solder joint is formed, as shown in FIG. 7A. In someembodiments, the calculation of the height and volume of the solderjoint is performed based on the following equations.

V _(lead) =πr _(lead) ² h  (7)

V _(barrel) =πr _(barrel) ² h  (8)

V _(required) =πh(r _(barrel) ² −r _(lead))  (9)

Where, V_(lead) is the volume of component lead; V_(barrel) is thevolume of through hole barrel; V_(required) is the volume of solderrequired to fill the barrel, r_(lead) is the (though hole) componentlead radius; r_(barrel) is through hole barrel radius; and h is theboard thickness, as shown in FIG. 7A.

FIG. 7A shows some exemplary solder joints, the image of which iscaptured by the two cameras, for through hole components, according tosome embodiments of the present invention. FIG. 7B shows some exemplarysolder joints, the image of which is captured by the two cameras, forsurface mount components, according to some embodiments of the presentinvention. In this case, the invention compares the height of the entireload to a predetermined reference height (a desired height) to form aparabolic or linear shape. Once the identified shape area is equivalentto a predefined percentage of the load (barrel) surface area within apredefined tolerance, a good solder is formed for the surface mountcomponent. As shown in FIG. 7B, for a larger surface mount component,the solder joint is formed on the side of the component as a parabolicshape. However, for a smaller surface mount component, the solder jointis formed on the side of the component as a linear shape since thecamera can only capture a linearly filled area due to the small size ofthe component.

It will be recognized by those skilled in the art that variousmodifications may be made to the illustrated and other embodiments ofthe invention described above, without departing from the broadinventive step thereof. It will be understood therefore that theinvention is not limited to the particular embodiments or arrangementsdisclosed, but is rather intended to cover any changes, adaptations ormodifications which are within the scope and spirit of the invention asdefined by the appended claims.

What is claimed is:
 1. A soldering station comprising: a solderingcartridge having a soldering tip; a power supply for delivering power tothe soldering tip; an indicator; and a processor including associatedcircuits for determining a thickness of an intermetallic component (IMC)of a soldering joint formed by the soldering tip performing a solderingoperation, and determining whether the thickness of the IMC is within apredetermined range, wherein the indicator indicates that a reliablesoldering joint connection is formed, when the processor determines thethickness of the IMC is within the predetermined range.
 2. The solderingstation of claim 1, wherein the processor further performs a preliminaryvalidation by measuring a temperature of the soldering tip.
 3. Thesoldering station of claim 1, wherein the processor further monitors apower level delivered to the soldering tip to detect liquidusoccurrence; and determines the thickness of the IMC based on detectedliquidus occurrence.
 4. The soldering station of claim 1, whereindetermining whether the thickness of the IMC is within a predeterminedrange is performed within a predetermined cooling time period.
 5. Thesoldering station of claim 1, further comprising a memory for storingdata related to the cartridge, and wherein the processor identifies thetype of the soldering cartridge being used and obtains informationrelated to the identified cartridge by retrieving data from the memory.6. The soldering station of claim 5, wherein data related to thecartridge stored in the memory includes one or more of a part number,lot code, a serial number, a total usage, a total point, a tipmass/weight, a tip configuration, an authentication code, a thermalefficiency, and a thermal characteristic.
 7. The soldering station ofclaim 1, further comprising a temperature sensor for measuring thetemperature of the soldering tip.
 8. The soldering station of claim 1,wherein the processor detects the liquidus occurrence when the monitoredpower is declining from a peak.
 9. A method performed by a solderingstation for a soldering joint connection validation, the solderingstation including a soldering cartridge having a soldering tip, themethod comprising: determining that a soldering event has started bymeasuring a power level delivered to the soldering tip, within a firstpredetermined time period; monitoring the power level delivered to thesoldering tip to detect liquidus occurrence; determining a thickness ofan intermetallic component (IMC) of the soldering joint as a function ofsoldering time and soldering tip temperature, after detecting theliquidus occurrence; determining whether the thickness of the IMC iswithin a predetermined range; and indicating that a reliable solderingjoint connection is formed, when the thickness of the IMC is within thepredetermined range.
 10. The method of claim 9, further comprisingidentifying a type of the soldering cartridge being used by thesoldering station and obtaining information related to the identifiedcartridge.
 11. The method of claim 10, wherein identifying a type of thesoldering cartridge being used and obtaining information related to theidentified cartridge comprises retrieving data from a memory within thesoldering station, or from a memory remote from the soldering station.12. The method of claim 9, further comprising performing a preliminaryvalidation by measuring a soldering tip temperature, after the solderingevent has started.
 13. The method of claim 9, wherein the soldering tiptemperature is determined by measuring an impedance of the soldering tipand determining the soldering tip temperature as a function of themeasured impedance.
 14. The method of claim 9, wherein the soldering tiptemperature is determined by defining a thermal efficiency factor for ageometry of the soldering tip and determining the soldering tiptemperature as a function of the thermal efficiency and the powereddelivered to the soldering tip.
 15. The method of claim 9, wherein theliquidus occurrence is detected when the monitored power is decliningfrom a peak.
 16. The method of claim 9, wherein the predetermined rangeof the thickness of the IMC is 1 μm-4 μm.
 17. A method performed by asoldering station for a soldering joint connection validation, thesoldering station including a camera for capturing respective images ofthe soldering joint from different views, the method comprising:determining an amount of solder needed for the soldering joint bycapturing a reference image of the soldering joint by the camera, beforea soldering event for forming the soldering joint starts; capturing acurrent image of the soldering joint by the camera, after the solderingevent starts to dispense solder at the soldering joint; comparing avalue of each pixel in the current image to corresponding pixel valuesin the reference image to detect any color changes of the pixels todetect an occurrence of a liquidus of the dispensed solder; afterdetection of the occurrence of the liquidus, determining an amount ofthe dispensed solder from the current image; comparing the amount of thedispensed solder to the determined amount of solder needed; repeatingthe comparing of the amount of the dispensed solder until the dispensedsolder has filled the soldering joint, within a predetermined tolerance;and activating an indicator to indicate a good soldering jointconnection, when the dispensed solder has filled the soldering jointwithin the predetermined tolerance.
 18. The method of claim 17, whereindetermining an amount of solder needed comprises of determining anamount of solder needed to fill in a barrel of a hole for a through holecomponent, or to fill in a surface of a barrel of a hole for a surfacemount component.
 19. The method of claim 17, wherein comparing theamount of the dispensed solder to the determined amount of solder neededcomprises of comparing a color value of each pixel in the current imageto corresponding pixel color values in the reference image, in relationto a known color pixel value of solder.
 20. The method of claim 19,wherein detection of the occurrence of the liquidus of the dispensedsolder is determined when all of the pixel color values in the lastcurrent image are equal to the known color pixel value of solder, withina tolerance range.
 21. A soldering station with automatic validation ofconnection of a soldering joint comprising: a soldering tip; a powersupply for delivering power to the soldering tip; a camera for capturingan image of the soldering joint; an indicator; and a processor includingassociated circuits for validation of the connection of the solderingjoint, wherein the camera captures a reference image of the solderingjoint, before a soldering event starts, the processor determines anamount of solder needed determining an amount of solder needed for thesoldering joint, from the reference image, the camera captures a currentimage of the soldering joint, after the soldering event starts, theprocessor compares a value of each pixel in the current image tocorresponding pixel values in the reference image to detect any colorchanges of the pixels in the current images due to spread of a dispensedsolder, as the soldering event progresses, the camera repeats capturinga current image and the processor repeats comparing a value of eachpixel, until all the pixels in the current images are determined to bepixels of the dispensed solder to detect an occurrence of a liquidus ofthe dispensed solder, after detection of the occurrence of the liquidus,the processor determines how much of the dispensed solder is dissipatedinto the soldering joint; and an indicator to indicate a good solderjoint connection, when the dispensed solder has filled the solderingjoint within a predetermined tolerance.
 22. The soldering station ofclaim 21, wherein the processor compares a color value of each pixel inthe current image to corresponding pixel color values in the referenceimage, in relation to a known color pixel value of solder.
 23. Asoldering station comprising: a soldering cartridge having a solderingtip; a power supply for delivering power to the soldering tip; anindicator; and a processor including associated circuits for monitoringa power level delivered to the soldering tip by the power supply todetect liquidus occurrence and determining a thickness of anintermetallic component (IMC) of a soldering joint formed by thesoldering tip performing a soldering operation, wherein the indicatorindicates that a reliable soldering joint connection is formed, when theprocessor determines the thickness of the IMC is within a predeterminedrange.